1. Field of the Invention
The present invention relates to a recording device such as an ink jet recording device. More particularly, the present invention relates to a recording device that can operate in a plurality of recording modes.
2. Description of Related Art
Conventionally, ink jet recording devices are employed in image forming devices such as printers, facsimile machines, and copy machines. There has been proposed an ink jet recording device of a type that controls the waveform of a driving pulse. Control of the driving-pulse waveform can adjust the ink ejection amount or the diameter of an ink dot attached on a recording medium. It is therefore possible to calibrate the variations of ink dots on the recording medium. It is also possible to perform a multi-tone or gradation recording. For example, Japanese Laid-Open Patent Application Kokai No.57-160654 describes driving an electromechanical transducer with driving pulses. The driving pulses are prepared by selecting one or more pulses out of a plurality of pulses in a predetermined pulse train. The electromechanical transducer is provided for each nozzle. The electromechanical transducer allows several ink particles to be ejected from the corresponding nozzle. The ink particles are different in their flying speeds and in their diameters. The ink particles join together into a single ink particle while they fly toward a recording medium. When the single ink particle reaches the recording medium, a single ink dot is produced on the recording medium.
In this type of recording device, a pulse selecting circuit is provided for selecting driving pulses for each nozzle. When the total number of nozzles increases in order to enhance the integrality and the recording density of the recording device, the structure of the pulse-selecting circuit becomes complicated. The entire circuit structure of the driving circuit becomes large. The number of the signal lines increases. The driving circuit becomes expensive.
There has been proposed a recording device of another type that can produce an image tone or gradation without greatly increasing the scale of the driving circuit or the number of signal lines. Representative examples of this type of recording devices are disclosed by Japanese Laid-Open patent application Kokai Nos.11-91143 and 2000-117980. The recording devices disclosed by those publications are provided with several waveform generators. The waveform generators produce several driving waveforms which are different in their pulse widths or in their amplitudes (voltage amounts). A driving waveform selector is provided to select, in accordance with image information, one waveform from the several waveforms. The selected waveform is applied to a driving element such as a piezoelectric actuator, thereby attaining gradation recording.
In order to maintain dot diameters uniform, it is desirable to perform a dot history-based recording control. The dot history-based recording control is performed dependently on whether dots have been recorded or not at the preceding recording operation and on whether dots will be recorded or not at the next recording operation while the recording head is scanned along the main scanning direction. Japanese Laid-Open patent application Kokai No.6-155732 discloses a circuit that attains the dot history-based recording control. The circuit includes several waveform generators which generate several driving waveforms. The circuit also includes a selector which selects a proper driving waveform, among the several driving waveforms, dependently on the dot history of ink ejection.